BATTERY INVERTER SYSTEMS

BATTERY INVERTER SYSTEMS

Battery Inverter systems can provide CLEAN and Uninterruptible Electrical power to areas of a facility with sensitive electronics. The reason to install a Battery Inverter system is to prevent National Utility Power Outages and Power Quantity from affecting equipment performance. The simplest form of a battery inverter is a UPS (Uninterruptible Power Supply).

There are basically three types of UPSs:

Off line (Modified Sine wave & Sine wave)

Off line with Voltage Interaction

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OFF LINE UPSs

Off Line UPSs are in standby mode in other words the utility power is pasted on to the output until the utility voltage is out of tolerance and the system electronically switches to battery/inverter. The voltage tolerance typically for this type of inverter is 5%. As I have from in the 3rd world setting, this is an impossible parameter to work with as the national utilities typical voltage tolerance is +10% and -25%. This UPS will be constantly switching to batteries with little time to recharge. These units tend to fail in less than a year. The less expensive units do not output a sine wave when running on battery/inverter. Most electronics tolerant this waveform but this electrical output has caused many problems with electronics with timing circuits and critical data level inputs. Obviously, I would not recommend this device

The OFF Line Interactive UPS is much better investment as the UPS has circuitry that will regulate the incoming power within specific levels. Typically the tolerances are 15% which is acceptable during daytime use. The cost of these UPS is more than double of an Off Line non Interactive UPS.

ON LINE UPSs

The On Line UPS has an output that is always supplied from the battery/inverter circuitry. The input voltage if it is in tolerance is used only to charge the batteries. This is the most expensive UPS but is essential from sensitive electronics.

One of the major concerns of a UPS or Battery/Inverter system is how long will it supply electrical power once the input or national utility power is not available. This is a function of the battery capacity. Smaller UPSs have a fixed battery capacity yielding about 5-7 minutes of operation depending on the electrical demand. The larger system which I am about to describe can have large battery banks to last many hours of operation.

Larger UPS or Battery/Inverter system range from 5 KW to 30 KW. These can be either single phase or three phase depending on the application. These units are generally Off Line with built in battery charging circuitry. The electronic switching time from input power to battery inverter power typically is 120 milliseconds on the smaller systems to 80 milliseconds on the larger systems depending on manufacturer. Just as a point of reference, typical electronics can handle a brown out or outage of 120-150 milliseconds without shutting down.

The purpose of the larger battery/inverters systems is to reduce the diesel generator set run time using the battery band as the energy storage source.